1. Field of the Invention
This invention relates to an interlayer connection structure, and more particularly to an improved interlayer connection structure in which a branchxe2x80xa2joint connection between a bus bar layer, having a plurality of bus bars, and a wire layer, having a plurality of wires, is effected.
2. Description of the Related Art
There has been proposed a so-called interlayer connection structure used as a wiring connection structure capable of achieving a high-density branchxe2x80xa2joint connection of the wiring in an electric connection box, such as a branch box, used in the connection of an electric system of an automobile.
In this structure, a branchxe2x80xa2joint connection between a bus bar layer, having a plurality of bus bars, and a wire layer, having a plurality of wires, is effected through press-connecting terminal portions formed on the bus bars.
FIG. 14 shows one such conventional interlayer connection structure.
The interlayer connection structure, shown in this Figure, is disclosed in JP-A-4-92309 directed to a flat wire harness-producing method, and this structure comprises a bus bar board 1 of an insulative material, having a plurality of juxtaposed slits 1a formed therein, a plurality of junction bars (bus bars) 3a, 3b, 3c, 3d and 3e press-fitted in the slits 1a to form a bus bar layer, and a plurality of wires 5, which forms a wire layer, and are laid on the bus bar layer.
Each of the junction bars 3a, 3b, 3c, 3d and 3e has tab terminals (connector terminals) T1, formed respectively at opposite ends thereof, and also has press-connecting terminal portions 14 formed on one longitudinal side edge thereof, the press-connecting terminal portion 14 having press-connecting end blades 14a for press-connection to the wire 5. In this illustrated example, each tab terminal T1 is connected to a male terminal (not shown), received in a connector 17, 18, through a relay terminal 16 of a female-female type.
The wires 5 are so-called sheathed (or covered) wires, and are arranged on the bus bar board 1 at predetermined intervals, and extend in a direction perpendicular to the direction of extending of the junction bars 3a, 3b, 3c, 3d and 3e. These wires 5 are press-connected to the predetermined press-connecting terminal portions 14 of the junction bars 3a, 3b, 3c, 3d and 3e, respectively. A cover 19, having press-connecting blade relief holes 21 formed therethrough for preventing the interference thereof with the press-connecting end blades 14a, is put on the bus bar board 1, thus effecting the desired branchxe2x80xa2joint connection.
In the above conventional interlayer connection structure, the press-connecting terminal portions 14 are formed integrally on the junction bars 3a, 3b, 3c, 3d and 3e, and the positions of formation of the projected press-connecting terminal portions 14 are determined for each junction bar 3a, 3b, 3c, 3d, 3e, depending on the positions of the associated wires to be connected respectively to these terminal portions 14.
Therefore, in order to achieve a wide variety of branchxe2x80xa2joint connections for the plurality of wires 5, many kinds of junction bars 3a, 3b, 3c, 3d and 3e, having the press-connecting terminal portions 14 projecting from different positions, must be prepared as shown in the drawings. Therefore, the number of kinds of bus bars, used to form the bus bar layer, increases, and the number of the component parts increases, and this has invited a problem that the production cost increases.
It is an object of this invention to overcome the above problems, and more specifically to provide an interlayer connection structure in which a wide variety of branchxe2x80xa2joint connections can be achieved without increasing kinds of bus bars used to form a bus bar layer.
The above object of the invention has been achieved by an interlayer connection structure comprising:
an insulative bus bar board having a plurality of juxtaposed bus bars of an electrically-conductive material mounted thereon, the bus bar board having a plurality of rows of terminal holding openings each row of which are formed in the bus bar board, and are spaced at predetermined intervals along a longitudinal side edge of a respective one of the bus bars;
press-connecting terminal members mounted respectively in the corresponding terminal holding openings to be electrically connected respectively to the corresponding bus bars; and
a plurality of wires press-connected to press-connecting end blades of the corresponding press-connecting terminal members extending through the terminal holding openings;
wherein a branchxe2x80xa2joint connection between a bus bar layer, formed by the plurality of bus bars, and a wire layer, formed by the plurality of wires, is effected through the press-connecting terminal members.
In the above construction, the positions of mounting of the press-connecting terminal members on each bus bar can be easily changed arbitrarily by selectively changing the terminal holding openings in which the press-connecting terminal members are to be mounted, respectively. And, a variety of bus bar layers, having different mounting positions of the press-connecting terminal members, can be provided even by the use of a single kind of bus bars.
Therefore, there can be obtained the interlayer connection structure in which a wide variety of branchxe2x80xa2joint connections can be effected without increasing the kind of the bus bars used to form the bus bar layer. By thus reducing the kind of the bus bars to be used, the production cost can be reduced.
In the above interlayer connection structure, preferably, there is provided a wire-holding insulative board which has a plurality of wire-mounting grooves, in which the wires can be mounted in a fixed manner, respectively, and press-connecting blade relief holes for enabling the press-connecting end blades to be press-connected to the wires held in the wire-mounting grooves, and the wires are mounted on the wire-holding insulative board mated with the insulative bus bar board.
With this construction, the wire layer and the bus bar layer are formed on the separate insulative boards, respectively, and therefore the wire layer-forming operation and the bus bar layer-forming operation can be effected concurrently, and the time, required for the operation, can be reduced. The bus bar layer and the wire layer, thus formed respectively on the two insulative boards, are superposed together, and by doing so, the desired interlayer connection can be easily completed, and the efficiency of the operation can be enhanced.
Preferably, the plurality of bus bars are mounted on an obverse surface of the insulative bus bar board, and a plurality of wire-mounting grooves, in which the wires can be mounted in a fixed manner, respectively, are formed in a reverse surface of the insulative bus bar board.
With this construction, only one insulative board is required for effecting the interlayer connection between the pair of bus bar layer and wire layer, and therefore the thickness in the direction of stacking of the layers can be reduced. Therefore, the number of the component parts, used in the interlayer connection, is reduced, so that the cost can be reduced, and besides an electric connection box, using the interlayer connection, can be formed into a small size.
Preferably, contact portions, which face the press-connecting terminal members, are formed by bending respectively on those portions of at least one longitudinal side edge of the bus bar corresponding respectively to the terminal holding openings, and each of the press-connecting terminal members has a resilient contact piece portion for press-contact with the contact portion.
With this construction, each of the juxtaposed bus bars, mounted on the insulative bus bar board, can be electrically connected to the press-connecting terminal member through the resilient contact of the resilient contact piece portion of the press-connecting terminal member with the contact portion. Therefore, by suitably determining the amount of resilient deformation of the resilient contact piece portion and an elastic coefficient thereof, the good electrical connection can be obtained regardless of dimensional tolerances, developing between each of the juxtaposed bus bars, mounted on the insulative bus bar board, and the terminal holding openings. Therefore, the dimensional tolerances of the component parts can be made less strict, and therefore the production cost is reduced, so that the productivity can be enhanced.
Preferably, the terminal holding openings are formed in a staggered manner along the opposite longitudinal side edges of each of the bus bars.
With this construction, the interval between the adjacent terminal holding openings can be reduced to a half of the interval of the adjacent terminal holding openings in the interlayer connection structure in which the plurality of terminal holding openings spaced at the predetermined intervals only along one longitudinal side edge of the bus bar. Therefore, the pitch of the wires, forming the wire layer, can be reduced, and by doing so, the interlayer connection of a higher density can be achieved, and also the electric connection box, having the interlayer connection, can be formed into a small size.